Hot and cold water mixing valves of a type which are commonly used for showers in commercial establishments such as hospitals, hotels and school athletic departments have a removable plastic balancing chamber cartridge within a metallic valve housing. One example of such a mixing valve is the "Series 400 Hydroguard" manufactured by the MCC Powers Process Controls unit of Mark Controls Corporation. The cartridge contains the operative mixing mechanism and is sealed by O-ring seals to hot and cold water inlets and a mixing water outlet within the housing.
After an extended period of operation such valves begin to leak or otherwise fail and it becomes necessary to replace the mixing cartridge. A commonly available removal tool is provided for this purpose as illustrated in FIG. 1. This tool comprises a u-shaped wire having inwardly facing hooks formed in the extremities of the legs. A slide clamp contains two apertures and is slipped over the wire toward the closed end with each aperture receiving a leg. The two hooks are inserted into two front facing holes in a cartridge that is to be removed and engage material surrounding the holes. The slide clamp is than slid toward the clamped end until it engages a small holding notch in each leg. In this position the slide clamp maintains the tool in a closed clamped position so that the tool remains clamped to the cartridge with a reasonable degree of security.
When a cartridge is first installed in a housing it slides into and out of the housing relatively easily and the removal tool is fully adequate for this function. However, after several years of operation sediment from the water builds up on the seals and the cartridge becomes very difficult to extract. Frequently, the seals will tear before they break away from the housing. The removal tool shown in FIG. 1 has been found to be completely inadequate under such circumstances. The tool is incapable of providing the required pulling force under these circumstances.
As the tool is worked the legs bend inwardly. This allows the hooks to loosen and pull back through the engagement holes without pulling the cartridge from the housing. The cartridge must then be broken up into several pieces with a hammer and chisel in order to effect removal. This frequently takes three to four hours. Even if the tool did not pull away from the cartridge it is doubtful that the ceramic tile or other decorative wall facing that supports the valve would be sufficient to withstand the pulling force required to remove the cartridge from it housing.